Deck 12: Solids: Structures and Applications

Question 1

In the cesium chloride unit cell shown below, the cesium ions sit on the corners of a cube. What is the name of this unit cell?

A) simple cubic
B) chloride-centered cubic
C) face-centered cubic
D) cubic-centered
E) body-centered cubic

Answer 1

body-centered cubic

Question 2

A cubic closest-packed structure has hexagonally arranged layers of atoms stacking in the series ________

A) ababab.
B) abcabcabc.
C) abcbabcbabcba.
D) abacabacaba.
E) aaaaaa.

Answer 2

abcabcabc.

Question 3

Which statement does not describe a simple cubic unit cell?

A) It results from square packing of atoms in layers.
B) The atoms lie at the corners of a cube.
C) Each atom has 6 nearest neighbors.
D) The stacking pattern can be represented by aaaa.
E) Each unit cell contains 8 atoms.

Answer 3

Each unit cell contains 8 atoms.

Question 4

In the sodium chloride unit cell, the chloride ions form a cube in which each side is arranged like the following figure. The circles represent the positions of the chloride ions on one square face of the cube. All the other faces are the same. What is the name of this unit cell?

A) simple cubic
B) chloride-centered cubic
C) face-centered cubic
D) x-face cubic
E) body-centered cubic

Question 5

The hexagonal closest-packed crystal structure has a ________ layering pattern that produces a ________ unit cell.

A) ababab; hexagonal
B) ababab; face-centered cubic
C) abcabcabc; hexagonal
D) abcabcabc; face-centered cubic
E) abcabcabc; body-centered cubic

Question 6

Identify the solid that has a high melting point, is hard and brittle, and conduct electricity when liquefied.

A) a molecular solid
B) a metal
C) a covalent network
D) an ionic solid
E) an amorphous solid

Question 7

Which statement A-D does not describe a simple cubic unit cell?

A) It results from square packing of atoms in layers.
B) The atoms lie at the corners of a cube.
C) Each atom has 6 nearest neighbors.
D) The stacking pattern can be represented by aaaa.
E) Statements A-D all correctly describe a simple cubic unit cell.

Question 8

The two types of closest-packed lattices are ________

A) cubic closest-packed and face-centered cubic.
B) cubic closest-packed and hexagonal closest-packed.
C) cubic closest-packed and random closest-packed.
D) cubic closest-packed and pyramidal closest-packed.
E) simple cubic and hexagonal closest-packed.

Question 9

The closest packing of spheres (such as oranges, cannonballs, or atoms) has the spheres ________

A) arranged in layers with each sphere surrounded by 4 other spheres in the layer.
B) arranged in layers with each sphere surrounded by 3 other spheres in the layer.
C) arranged in a square pattern with a sphere at each corner and one in the center of the square.
D) arranged in a square pattern with a sphere at each corner of the square.
E) arranged in layers with each sphere surrounded by 6 other spheres in the layer.

Question 10

At a historic Civil War battleground, a stack of cannonballs looked like the picture below on the far left. Removing the top cannonball resulted in the middle view, and removing the next layer resulted in the view on the right. What sort of packing was used in stacking the cannonballs?

A) cannonball closest-packed
B) hexagonal closest-packed
C) cubic closest-packed
D) random-packed
E) body-centered closest-packed

Question 11

A hexagonal closest-packed structure has hexagonally arranged layers of atoms stacking in the series ________

A) ababab.
B) abcabcabc.
C) abcbabcbabcba.
D) abacabacaba.
E) aaaaaa.

Question 12

Which type of solid is held together by relatively weak dispersion forces?

A) ionic solid
B) metal
C) molecular solid
D) ceramic
E) semiconductor

Question 13

Which of the following is true regarding the attractive force that holds sodium chloride in the solid state?
I.It is electrostatic.
II.It is termed ionic bonding.
III.It depends on the distance between the sodium and chloride.
IV.It only operates between adjacent sodium and chloride.

A) I and II only
B) II and III only
C) I, II, and III only
D) II and IV only
E) I-IV are all true statements.

Question 14

Which of the following unit cells has the lowest packing efficiency?

A) simple cubic
B) face-centered cubic
C) body-centered cubic
D) both face-centered and body-centered cubic
E) Simple, face-centered, and body-centered cubic all have the same packing efficiency.

Question 15

Ionic solids have ________ melting points, and are ________.

A) high; malleable
B) high; brittle
C) low; malleable
D) low; brittle
E) high; soft

Question 16

Which of the following contribute to the arrangement of ions in the unit cells of an ionic solid?
I.The empirical formula
II.The relative radii of the ions
III.The shape of polyatomic ions

A) I and II only
B) II and III only
C) I and III only
D) I only
E) I, II, and III

Question 17

The cubic closest-packed crystal structure has a ________ layering pattern that produces a ________ unit cell.

A) ababab; hexagonal
B) ababab; face-centered cubic
C) abcabcabc; hexagonal
D) abcabcabc; face-centered cubic
E) abcabcabc; body-centered cubic

Question 18

Pure solid metals ________

A) do not crystallize.
B) are amorphous.
C) often crystallize in closest-packed structures.
D) often crystallize in very complex unit cells.
E) are like liquids with the nuclei flowing through a sea of electrons.

Question 19

The face-centered cubic structure is also known as ________

A) cubic closest-packed.
B) hexagonal closest-packed.
C) square closest-packed.
D) spherical closest-packed.
E) none of the above, as it is not a closest-packed pattern.

Question 20

Which is not true about a crystallographic unit cell?

A) It repeats throughout a crystalline structure in three dimensions.
B) It fills all the space in the crystalline lattice.
C) Its dimensions can be measured with X-rays.
D) It has corners with 90° angles.
E) It represents the smallest repeating unit in the crystal.

Question 21

Aluminum (Al) crystallizes as a face-centered unit cell with an edge length of 404 pm. What is the atomic radius of aluminum?

A) 143 pm
B) 202 pm
C) 286 pm
D) 175 pm
E) 808 pm

Question 22

If a face-centered cubic unit cell has a volume of 1.447* 10⁸ pm³ and the ions at the corners touch the ion on the face, what must be the ion's radius?

A) 186 pm
B) 388 pm
C) 4,243 pm
D) 125 pm
E) 1,050 pm

Question 23

Polonium crystallizes in a simple cubic pattern. How many polonium atoms are in each unit cell?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 24

Copper crystallizes in a face-centered cubic pattern. How many copper atoms are in each unit cell?

A) 2
B) 4
C) 8
D) 12
E) 14

Question 25

Compare the packing efficiency of face-centered cubic aluminum and face-centered cubic lead.

A) The efficiency of packing in the aluminum unit cell is higher because the aluminum atom is larger.
B) The efficiency of packing in the lead unit cell is higher because the lead atom is larger.
C) The efficiencies of packing in the unit cells of these two metals are the same.
D) The efficiency of packing in the aluminum unit cell is higher because the aluminum atom is smaller.
E) The efficiency of packing in the lead unit cell is higher because the lead atom is smaller.

Question 26

Gold (Au) has a face-centered cubic structure with a unit cell edge length of 407.8 pm. What is the calculated value of the density of gold based on this information?

A) 15.78 g/cm³
B) 19.28 g/cm³
C) 9.64 g/cm³
D) 4.82 g/cm³
E) 11.6 g/cm³

Question 27

Iron (Fe) crystallizes as a body-centered unit cell with an edge length of 287 pm. What is the atomic radius of iron?

A) 99 pm
B) 114 pm
C) 124 pm
D) 143 pm
E) 256 pm

Question 28

Which unit cell contains the most atoms?

A) fcc
B) bcc
C) cubic
D) both fcc and bcc
E) None of the above, as fcc, bcc, and cubic contain the same number of atoms.

Question 29

Aluminum (Al) has a density of 2.70 g/cm³ and crystallizes in a face-centered cubic structure. What is the unit cell edge length?

A) 2.47 *10^-3 pm
B) 40.0 pm
C) 405 pm
D) 321 pm
E) 255 pm

Question 30

If a body-centered cubic unit cell has a volume of 1.447 * 10⁸ pm³, what must be the dimension of the cube's edge?

A) 1.131 *10⁸ pm
B) 110 pm
C) 1.20*10⁴ pm
D) 525 pm
E) 367 pm

Question 31

Silver crystallizes with a face-centered cubic unit cell. The edge length is 407.7 pm. What is the volume of this unit cell?

A) 7.68 x 10⁷ pm³
B) 6.78 x 10⁷ pm³
C) 8.67 x 10⁷ pm³
D) 9.87 x 10⁷ pm³
E) 3.88 x 10⁷ pm³

Question 32

How many nearest neighbor atoms are there around each atom in a body-centered cubic unit cell?

A) 4
B) 6
C) 8
D) 10
E) 12

Question 33

Iron crystallizes in a body-centered cubic pattern. How many iron atoms are in each unit cell?

A) 1
B) 2
C) 4
D) 8
E) 9

Question 34

How many nearest neighbor atoms are there around each atom in a face-centered cubic unit cell?

A) 4
B) 6
C) 8
D) 10
E) 12

Question 35

The alpha form of polonium (Po) has a density of 9.196 g/cm³ and crystallizes in a simple cubic structure. What is the atomic radius of polonium?

A) 119 pm
B) 168 pm
C) 266 pm
D) 335 pm
E) 419 pm

Question 36

Compare the packing efficiency of face-centered cubic gold and face-centered cubic copper.

A) The efficiency of packing in the gold unit cell is higher.
B) The efficiency of packing in the copper unit cell is higher.
C) The efficiencies of packing in the unit cells of these two metals are the same.
D) Packing efficiencies are not defined for metals.
E) There is no way to compare without further information.

Question 37

The alpha form of polonium (Po) crystallizes as a simple cubic unit cell with an edge length of
335 pm. What is the atomic radius of polonium?

A) 84 pm
B) 168 pm
C) 335 pm
D) 175 pm
E) 808 pm

Question 38

Compare the packing efficiency of face-centered cubic gold and face-centered cubic sodium chloride considering all the atoms.

A) The efficiency of packing in the gold unit cell is higher.
B) The efficiency of packing in the sodium chloride unit cell is higher.
C) The efficiencies of packing in the two lattices are the same.
D) Packing efficiencies cannot be defined for one or both of these.
E) There is no way to compare without further information.

Question 39

How many nearest neighbor atoms are there around each atom in a simple cubic unit cell?

A) 4
B) 6
C) 8
D) 10
E) 12

Question 40

Which of the following unit cells has the highest packing efficiency?

A) simple cubic
B) face-centered cubic
C) body-centered cubic
D) both face-centered and body-centered cubic
E) Simple, face-centered, and body-centered cubic all have the same packing efficiency.

Question 41

In a two-component alloy the more abundant metal can be thought of as the solvent while the less abundant metal can be thought of as the solute. Which of the following would not change the position of atoms in the solvent's unit cell?
I.a solute with the same atomic radius as the solvent
II.a solute that was sufficiently small to fit into holes in the solvent's unit cell
III.a solvent that was sufficiently small to fit into holes in the solute's unit cell

A) I only
B) II only
C) III only
D) I or II
E) I, II, or III

Question 42

Aluminum alloys are more desirable than steel in some applications because of their relatively ________

A) low density.
B) low cost.
C) high luster.
D) high warmth to touch.
E) high conductivity.

Question 43

Iron (Fe) has a density of 7.874 g/cm³ and crystallizes in a body-centered cubic structure. What is the atomic radius of iron?

A) 99 pm
B) 114 pm
C) 124 pm
D) 143 pm
E) 255 pm

Question 44

Which of the following refers to an alloy in which the composition is variable and the elements have comparable radii?

A) intermetallic
B) interstitial
C) stoichiometric
D) substitutional
E) homogeneous

Question 45

Band theory of bonding in solids ________

A) is an extension of molecular orbital theory.
B) describes bonds as rubber bands.
C) does not apply to any type of solid other than metals.
D) explains bond formation in metals, but not their physical properties.
E) All of the above are correct.

Question 46

Gold has a face-centered cubic structure with a unit cell edge length of 407.8 pm. What is the contribution to the density from each individual gold atom?

A) 21.44 g/cm³
B) 26.20 g/cm³
C) 13.1 g/cm³
D) 6.55 g/cm³
E) 19.28 g/cm³

Question 47

Which statement regarding the formation of an alloy is correct?

A) Carbon forms an interstitial alloy with iron because their atomic radii are about the same.
B) Carbon forms a substitutional alloy with iron because their atomic radii are about the same.
C) Carbon forms an interstitial alloy with iron because carbon has a much smaller atomic radius.
D) Carbon forms a substitutional alloy with iron because carbon has a much smaller atomic radius.
E) Carbon forms an interstitial alloy with iron because carbon has a much larger atomic radius.

Question 48

Which of the following refers to an alloy in which the composition of the elements is constant?

A) intermetallic
B) interstitial
C) stoichiometric
D) substitutional
E) homogeneous

Question 49

Stainless steel is less susceptible to rusting than iron because ________

A) it is coated with plastic.
B) the metals other than iron in the alloy form protective oxides.
C) the carbon within the alloy polymerizes to form a protective film.
D) the silicon within the alloy oxidizes to form a protective silicate layer.
E) the intermetallic compound formed is less reactive.

Question 50

Metal solids are good conductors of electricity because ________

A) they are easily ionized.
B) their valence electrons are not localized.
C) they are easily reduced and oxidized.
D) they can be drawn into wires.
E) they are ductile.

Question 51

A tetrahedral hole in a crystal lattice is defined as ________

A) one-half of an octahedral hole.
B) the space between any number of atoms having tetrahedral edges.
C) the space between a cage of sp³ hybridized atoms, such as in diamond.
D) the space between a cluster of four adjacent atoms arranged in a tetrahedron.
E) a large hole having four flat sides arranged in a tetrahedral shape.

Question 52

The higher the carbon content in steel, ________

A) the stronger and more malleable it is.
B) the stronger and more brittle it is.
C) the weaker and more malleable it is.
D) the weaker and more brittle it is.
E) Any of these, depending on the formula of the interstitial compound.

Question 53

Which of the following refers to an alloy in which the composition of the elements is variable and one element must have a much smaller radius than the other?

A) intermetallic
B) interstitial
C) stoichiometric
D) substitutional
E) inhomogeneous

Question 54

Bronze that is composed of 10% tin and 90% copper is ________

A) a substitutional alloy.
B) an interstitial alloy.
C) a doped semiconductor.
D) a colloidal alloy.
E) an intermetallic compound.

Question 55

The bonding in solid-state metals can be described as ________

A) nonexistent.
B) a covalent network.
C) an electron sea.
D) highly directional.
E) ionic.

Question 56

Electrical and thermal conductivity in metals ________

A) is explained by a dipolar coupling model.
B) is explained by band theory.
C) is explained by matrix isolation techniques.
D) is explained by temporary ionization.
E) is a function of the level of contamination by excess electrons.

Question 57

In comparing the density of bronze composed of 20% tin to the density of pure copper, ________

A) the density of the bronze is higher.
B) the density of the bronze is lower.
C) the density of the bronze is the same.
D) the density of the bronze depends on whether the tin or the copper occupies holes.
E) It cannot be determined, because only the 1:1 intermetallic compound of tin and copper has ever been observed.

Question 58

Aluminum is resistant to corrosion because of ________

A) its positive oxidation potential.
B) its low density.
C) the formation of a protective surface film of aluminum oxide.
D) the formation of a protective surface film of aluminum nitride.
E) its lack of reactivity toward oxygen.

Question 59

Which of the following can be varied to change the physical properties of an alloy?
I.The elements used
II.The proportions used
III.The type of hole each element occupies

A) I only
B) II only
C) III only
D) I and II only
E) I, II, and III

Question 60

In addition to carbon and iron, stainless steel contains ________

A) Teflon and polyethylene.
B) gold and silver.
C) copper and nickel.
D) chromium and nickel.
E) platinum.

Question 61

The face-centered cubic unit cell has ________ tetrahedral holes.

A) 0
B) 1
C) 4
D) 8
E) 12

Question 62

Which statement about a semiconductor is not correct?

A) Both electrons in the conduction band and holes in the valence band conduct electricity.
B) The band gap becomes smaller with increasing temperature.
C) The band gap is smaller than in an insulator.
D) Adding an impurity can increase the conductivity.
E) Conductivity increases with increasing temperature.

Question 63

When Ge is doped with Ga, it produces a(n) ________-type semiconductor.

A) p
B) n
C) q
D) np
E) No semiconductor will be produced.

Question 64

The molecular orbital description for metal bonding is different from that for diatomic molecules in that ________

A) there are no antibonding orbitals in the metal bonding description.
B) quantum theory no longer applies as the orbitals are continuous.
C) the orbitals are so close in energy that they are referred to as bands.
D) the increased number of electrons results in each bond being stronger.
E) All of the above are true.

Question 65

Which of the following elements are semiconductors?
C, Si, Ge, Sn

A) C and Si only
B) Si and Ge only
C) Ge and Sn only
D) None of these elements are semiconductors unless a dopant is added.
E) All of these elements are semiconductors.

Question 66

GaAs and AlGaAs₂ are examples of ________ semiconductors.

A) light-emitting diode (LED)
B) sound-emitting
C) np
D) non-
E) dual voltage

Question 67

The band structure of semiconductors differs from that of metal conductors in that ________

A) metal bands are relatively empty, while semiconductor bands are nearly full.
B) metal bands are nearly full, while semiconductor bands are relatively empty.
C) metal conduction bands are lower in energy than valence bands, while semiconductor conduction bands are higher in energy than valence bands.
D) metal conduction bands are higher in energy than valence bands, while semiconductor conduction bands are lower in energy than valence bands.
E) valence bands in metals are either partially empty or overlap with conduction bands, while these bands in semiconductors are separated by a small gap.

Question 68

Light-emitting diodes are semiconductors that emit light when a current is passed through them. What is the key factor that must be changed to change the wavelength of the emitted light in an LED?

A) the width of the valence band
B) the width of the conduction band
C) the width of the band gap
D) the magnitude of the current
E) the type of semiconductor (p vs. n)

Question 69

Which of the following can be used to increase the conductivity of any semimetal?
I.Adding an element with one additional valence electron
II.Adding an element with one fewer valence electron
III.Lowering the temperature

A) I only
B) II only
C) III only
D) I and II only
E) I, II and III

Question 70

The center of a cubic hole is found ________

A) at the center of a simple cubic lattice.
B) on the edges of a simple cubic lattice.
C) on the faces of a body-centered cubic lattice.
D) at the center of a face-centered cubic lattice.
E) at eight sites within a face-centered cubic lattice.

Question 71

A face-centered cubic unit cell contains ________ octahedral holes.

A) 1
B) 4
C) 8
D) 12
E) 13

Question 72

When Si is doped with P, it produces a(n) ________-type semiconductor.

A) p
B) n
C) q
D) np
E) No semiconductor will be produced.

Question 73

Which element would be used to dope germanium to produce an n-type semiconductor?

A) Ga
B) Sn
C) Si
D) As
E) Cu

Question 74

In the cubic closest-packed structure of sodium chloride, which ions are touching or nearly touching?
I.Sodium ions and sodium ions
II.Chloride ions and chloride ions
III.Sodium ions and chloride ions

A) I only
B) II only
C) III only
D) II and III only
E) I and III only

Question 75

Which statement A-D regarding semiconductors is not correct?

A) An undoped semiconductor does not conduct electricity because it has a filled valence band and a vacant conduction band.
B) Doping silicon with phosphorous produces an n-type semiconductor.
C) An n-type semiconductor has electrons in its conduction band.
D) Doping silicon with gallium removes electrons from the valence band to enhance the conductivity.
E) Statements A-D all are correct.

Question 76

Which statement regarding the electronic structure of solids is not correct?

A) The band theory of solids is like molecular orbital theory in that the electronic wave function is delocalized to some extent over all the constituent atoms.
B) In solids that are electrical insulators, there is a large gap between a filled valence band and a vacant conduction band.
C) In semiconductors, the gap between the valence band and conduction band is small, so a few electrons have sufficient thermal energy to be found in the conduction band.
D) n- and p-type semiconductors can be produced by doping a semimetal with an element from a different group.
E) Germanium doped with arsenic is a p-type semiconductor.

Question 77

A face-centered cubic unit cell has a(n) ________ in its center.

A) tetrahedral hole
B) octahedral hole
C) atom
D) square planar hole
E) cubic hole

Question 78

When silicon is doped with gallium, electrical conduction increases because ________

A) gallium has fewer valence electrons than silicon, so holes are created in the valence band of silicon.
B) gallium has more valence electrons than silicon, so electrons are added to the conduction band of silicon.
C) gallium causes electrons to be transferred from the valence band of silicon to the conduction band of silicon.
D) gallium causes electrons to be transferred from the conduction band of silicon to the valence band of silicon.
E) gallium is a better conductor of electricity than silicon.

Question 79

Which element would be used to dope silicon to produce a p-type semiconductor?

A) boron (B)
B) carbon (C)
C) aluminum (Al)
D) phosphorus (P)
E) germanium (Ge)

Question 80

Molecular orbital theory can be applied ________

A) only to two adjacent metal atoms.
B) only to a few metal atoms that are very close to each other.
C) to any number of metal atoms.
D) to nonmetals only, not to metals.
E) to nonmetals and ionic bonds only, not to metals.